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dc.contributor.authorChaurasia, Adarsh Kumaren
dc.date.accessioned2017-10-26T06:00:14Zen
dc.date.available2017-10-26T06:00:14Zen
dc.date.issued2016-05-03en
dc.identifier.othervt_gsexam:7716en
dc.identifier.urihttp://hdl.handle.net/10919/79789en
dc.description.abstractThe current state of the art in structural health monitoring is primarily reliant on sensing deformation of structures at discrete locations using sensors and detecting damage using techniques such as X-ray, microCT, acoustic emission, impedance methods etc., primarily employed at specified intervals of service life. There is a need to develop materials and structures with self-sensing capabilities such that deformation and damage state can be identified in-situ real time. In the current work, the inherent deformation and damage sensing capabilities of carbon nanotube (CNT) based nanocomposites are explored starting from the nanoscale electron hopping mechanism to effective macroscale piezoresistive response through finite elements based computational micromechanics techniques. The evolution of nanoscale conductive electron hopping pathways which leads to nanocomposite piezoresistivity is studied in detail along with its evolution under applied deformations. The nanoscale piezoresistive response is used to evaluate macroscale nanocomposite response by using analytical micromechanics methods. The effective piezoresistive response, obtained in terms of macroscale effective gauge factors, is shown to predict the experimentally obtained gauge factors published in the literature within reasonable tolerance. In addition, the effect of imperfect interface between the CNTs and the polymer matrix on the mechanical and piezoresistive properties is studied using coupled electromechanical cohesive zone modeling. It is observed that the interfacial separation and damage at the nanoscale leads to a larger nanocomposite irreversible piezoresistive response under monotonic and cyclic loading because of interfacial damage accumulation. As a sample application, the CNT-polymer nanocomposites are used as a binding medium for polycrystalline energetic materials where the nanocomposite binder piezoresistivity is exploited to provide inherent deformation and damage sensing. The nanocomposite binder medium is modeled using electromechanical cohesive zones with properties obtained through the Mori-Tanaka method allowing for different local CNT volume fractions and orientations. Finally, the traditional implementation of Material Point Method (MPM) is extended for composite problems with large deformation (e.g. large strain nanocomposite sensors with elastomer matrix) allowing for interfacial discontinuities appropriately. Overall, the current work evaluates nanocomposite piezoresistivity using a multiscale modeling framework and emphasizes through a sample application that nanocomposite piezoresistivity can be exploited for inherent sensing in materials.en
dc.format.mediumETDen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectCarbon Nanotubeen
dc.subjectNanocompositeen
dc.subjectPiezoresistivityen
dc.subjectElectron Hoppingen
dc.subjectComputational Micromechanicsen
dc.subjectStrain Sensingen
dc.subjectDamage Sensingen
dc.subjectCohesive Zoneen
dc.subjectInterface Damageen
dc.subjectMaterial Point Methoden
dc.titleComputational Micromechanics Analysis of Deformation and Damage Sensing in Carbon Nanotube Based Nanocompositesen
dc.typeDissertationen
dc.contributor.departmentEngineering Science and Mechanicsen
dc.description.degreePh. D.en
thesis.degree.namePh. D.en
thesis.degree.leveldoctoralen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineEngineering Mechanicsen
dc.contributor.committeechairSeidel, Gary D.en
dc.contributor.committeememberStaples, Anne E.en
dc.contributor.committeememberBatra, Romesh C.en
dc.contributor.committeememberKapania, Rakesh K.en
dc.contributor.committeememberCase, Scott W.en


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